This text is an excerpt from a book called "Philosophy 101" and explores the history of Western philosophy by examining the main ideas and contributions of various philosophers. The excerpt focuses on the contributions of pre-Socratic philosophers, major figures like Plato, Aristotle, and Descartes, and more contemporary thinkers like Nietzsche and Wittgenstein. The text provides an overview of their ideas, highlighting key concepts and arguments that have shaped Western philosophy. It also introduces specific philosophical problems like the "Ship of Theseus" paradox and the trolley problem, and how these problems continue to generate debate.